2.1 Solid Forms of Pharmaceutical Compounds
The identification and selection of a solid form of a pharmaceutical compound are complex, given that a change in solid form may affect a variety of physical and chemical properties, which may provide benefits or drawbacks in processing, formulation, stability, bioavailability, storage, handling (e.g., shipping), among other important pharmaceutical characteristics. Useful pharmaceutical solids include crystalline solids and amorphous solids, depending on the product and its mode of administration. Amorphous solids are characterized by a lack of long-range structural order, whereas crystalline solids are characterized by structural periodicity. The desired class of pharmaceutical solid depends upon the specific application; amorphous solids are sometimes selected on the basis of, e.g., an enhanced dissolution profile, while crystalline solids may be desirable for properties such as, e.g., physical or chemical stability (see, e.g., S. R. Vippagunta et al., Adv. Drug. Deliv. Rev., (2001) 48:3-26; L. Yu, Adv. Drug. Deliv. Rev., (2001) 48:27-42).
Whether crystalline or amorphous, solid forms of a pharmaceutical compound include single-component and multiple-component solids. Single-component solids consist essentially of the pharmaceutical compound or active ingredient in the absence of other compounds. Variety among single-component crystalline materials may potentially arise from the phenomenon of polymorphism, wherein multiple three-dimensional arrangements exist for a particular pharmaceutical compound (see, e.g., S. R. Byrn et al., Solid State Chemistry of Drugs, (1999) SSCI, West Lafayette). The importance of discovering polymorphs was underscored by the case of Ritonavir™, an HIV protease inhibitor that was formulated as soft gelatin capsules. About two years after the product was launched, the unanticipated precipitation of a new, less soluble polymorph in the formulation necessitated the withdrawal of the product from the market until a more consistent formulation could be developed (see S. R. Chemburkar et al., Org. Process Res. Dev., (2000) 4:413-417).
Additional diversity among the potential solid forms of a pharmaceutical compound may arise from the possibility of multiple-component solids. Crystalline solids comprising two or more ionic species may be termed salts (see, e.g., Handbook of Pharmaceutical Salts: Properties, Selection and Use, P. H. Stahl and C. G. Wermuth, Eds., (2002), Wiley, Weinheim). Additional types of multiple-component solids that may potentially offer other property improvements for a pharmaceutical compound or salt thereof include, e.g., hydrates, solvates, cocrystals and clathrates, among others (see, e.g., S. R. Byrn et al., Solid State Chemistry of Drugs, (1999) SSCI, West Lafayette). Moreover, multiple-component crystal forms may potentially be susceptible to polymorphism, wherein a given multiple-component composition may exist in more than one three-dimensional crystalline arrangement.
Cocrystals are crystalline molecular complexes of two or more non-volatile compounds bound together in a crystal lattice by non-ionic interactions. Pharmaceutical cocrystals are cocrystals of a therapeutic compound, e.g., an active pharmaceutical ingredient (API), and one or more non-volatile compound(s) (referred to herein as coformer). A coformer in a pharmaceutical cocrystal is typically a non-toxic pharmaceutically acceptable molecule, such as, for example, food additives, preservatives, pharmaceutical excipients, or other APIs. In recent years, pharmaceutical cocrystals have emerged as a possible alternative approach to enhance physicochemical properties of drug products.
The variety of possible solid forms creates potential diversity in physical and chemical properties for a given pharmaceutical compound. The discovery and selection of solid forms are of great importance in the development of an effective, stable and marketable pharmaceutical product.
2.2 Pomalidomide
Pomalidomide, which was previously referred to as CC-4047, and has a chemical name of 4-amino-2-(2,6-dioxopiperidine-3-yl)isoindoline-1,3-dione. Pomalidomide is a compound that inhibits, for example, LPS induced monocyte TNFα, IL-1β, IL-12, IL-6, MIP-1, MCP-1, GM-CSF, G-CSF, and COX-2 production, and may be used in treating various disorders. See, e.g., U.S. Pat. Nos. 5,635,517, 6,316,471, 6,476,052, 7,393,863, 7,629,360, and 7,863,297; and U.S. Patent Application Publication Nos. 2005/0143420, 2006/0166932, 2006/0188475, 2007/0048327, 2007/0066512, 2007/0155791, 2008/0051431, 2008/0317708, 2009/0087407, 2009/0088410, 2009/01317385, 2009/0148853, 2009/0232776, 2009/0232796, 2010/0098657, 2010/0099711, and 2011/0184025, the entireties of which are incorporated herein by reference. The compound is also known to co-stimulate the activation of T-cells. Pomalidomide has direct anti-myeloma tumoricidal activity, immunomodulatory activities and inhibits stromal cell support for multiple myeloma tumor cell growth. Specifically, pomalidomide inhibits proliferation and induces apoptosis of hematopoietic tumor cells. Id. Additionally, pomalidomide inhibits the proliferation of lenalidomide-resistant multiple myeloma cell lines and synergizes with dexamethasone in both lenalidomide-sensitive and lenalidomide-resistant cell lines to induce tumor cell apoptosis. Pomalidomide enhances T cell- and natural killer (NK) cell-mediated immunity, and inhibits production of pro-inflammatory cytokines (e.g., TNF-α and IL-6) by monocytes. Pomalidomide also inhibits angiogenesis by blocking the migration and adhesion of endothelial cells. Due to its diversified pharmacological properties, pomalidomide is useful in treating, preventing, and/or managing various diseases or disorders.
Pomalidomide and methods of synthesizing the compound are described, e.g., in U.S. Pat. Nos. 5,635,517, 6,335,349, 6,316,471, 6,476,052, 7,041,680, 7,709,502, and 7,994,327; and U.S. Patent Application Publication Nos. 2006/0178402 and 2011/0224440; the entireties of which are incorporated herein by reference.
Citation of any references in this Section is not to be construed as an admission that such references are prior art to the present application.